Carburetor



Jan. 2, 1934. 'F Q SCHRAMM 1,942,005

CARBURETOR Filed Oct. 17. 1931 2 Sheets-Sheet l @Ms/MM 2 Sheets-Sheet 2CARBURET OR Jan. 2, 1934.

Patented Jan. 2, 1934 UNITED STATES PATENT Erica f 1 Claim.

This invention relates to a carburetor for gas engines which willautomatically provide variations of mixtures of fuel and air fordifferent conditions of operation of the engine, such as changes fromslow speed to high speed and vice versa and changes in load conditions.

In carrying out this invention a slidable venturi is provided in thecarburetor which will assume different positions with respect to thefuel lll jetor jets at different times. The invention is suitable forcarburetors that are installed either vertically or horizontally or atan inclination to the vertical. l Y

One of the objects of this invention is to provide means that willoperate automatically under various load conditions so that suitablecar- Yburetion will result to meet the requirements for slow enginespeed and heavy load conditions to high speed under either light orheavy load conditions. n

The invention will loe-understood from the description in connectionwiththe accompanying drawings in which Fig. 1 is a vertical sectionthrough an illustrative embodiment of the invention and Fig. 2 is asimilar section partly brokenaway showing modifications of some of theparts.

Y In the drawings reference character 1 indicates a carburetor casing,which may be of any one of a number of well-known types having a baseportion 2 and a neck portion 3 havinga throttle valve 4 therein. Aflange 5 may be prov ded at the end of the neck portion by means ofwhich the carburetor can be attached to a manifold or a connection to amanifold.

The base portion of the carburetor is connected as indicated at 6 to theusual fioat chamber that is provided for maintaining a constant liquidlevel from which fuel is fed to the jets. Air is drawn by the suction inthe manifold through the carburetor in the well-known way through theinlet 7.

The venturi 8 which is provided in the neck portion 3 of the carburetorsurrounding-the tubes which feed gasoline is, in accordance with thisinvention, made longitudinally movable in the neck portion 3 and is sosituated that the smallest cross sectional area of the opening throughthis venturi is located approximately at the liquid level in the jet asmaintained by the float chamber. The venturi 8 may be provided with oneor more longitudinally extending slots 9 along the outside thereof. Pins10 extend into the longitudinal slots 9. Coil springs 11 are installed55 in the slots 9 between the lower ends of these slots and the pins toreturn the venturi 8 to its 'A' initial position after it has been movedtherefrom and the conditions whichV caused it to move have ceased. Smallbumper springs 11 are installed between the pins 10 and the upper endsof the 50 slots 9. f

In the illustrative embodiment of the invention shown in Fig. 1 aplurality of concentric tubes or jets 12, 13, 14 and 14 are shown forproviding liquid fuel to the carburetor. The innermost tube @5 12extends farther than the others. The intermediate tube 13 terminatesshort of the tube 12 and is large enough to provide an. annular spacebetween the two, and the two outermost tubes 14 and 14' are of the samelength and are short- 70 er. than the others. The tube 14 isalso largeenough to provide an annular space between it and the tube 13 and thetube 14' is large enough to provide an annular space between it and thetube 14. These tubes or jets are of such lengths 75 -that the Vouter orexit ends of the tubes 14 and 14' terminate approximately at'thesmallest portion of the opening'through the venturi 8 when the venturiis in its innermost position orl positi-on of greatest retraction bythesprings ll. .80 TheV tube 12 terminates even. with the narrowest portionof the venturi 8 when itis in Vits outermost positon and the tube 13terminates approximately half-way between the tubes 12 and 14. y

The tubes or jets 12, 13, 14 and 14 are fed from 85 the float chamber,as indicated at 15, andv the liquid levels in these three tubes areapproximately at the endof the outermost tubes 14 and 14'V when theengine starts. The outer walls of the tube 14 may be provided withperforations 90 16 so that the tubes 14 and 14 communicate with eachother and the feed 15 is provided with openings 17 so that fuel is feddirectly from it into each one of the tubes 12 and 13. Liquid fuelpasses from the end of the inlet 15 into the tube ,95 14.

In the modification shown in Fig. 2 annular recess 21 is provided alongthe inner surface of the neck portion 1 and an annular ring or rib 22 isprovided on the venturi 3 extending into the 1,00 recess 21. A coilspring 23 is installed in the recess 21 above the ring 22 to return theventuri 8' to its initial position and a bumper spring 24 is installedin the recess 2l below the ring 22.

The longest tube 25 is fed at the lower end "1,05 thereof through arestricted inlet 26 from a compartment 27 into which the feeder 15introduces the liquid fuel or gasolene. The intermediate tube 28communicates with said compartment 27 through a restricted opening 29and the tube 30 .1:10

communicates with said compartment 27 through a restricted opening 31.The outermost tube 30' communicates with the tube 30 through openings32.

The upper portions of the tubes or jets 25, 28, 30 and 30' aresurrounded by a draft tube 33 which is kept in place by means of thesupport 34 so that the outer end of the draft tube extends slightly lesstowards the outside than the outer end of the tube 25. The upper end ofthe draft tube 33 preferably terminates somewhat short of the smallestpart of the opening through the venturi 8'. The tubes 30 and 30terminate a considerable distance short of the outer end of the tube 25and the tube 28 terminatesr approximately half-way between the tubes 25and 30.

A removable plug 35 maybe provided through which the tube 25 can bewithdrawn and a removable plug 36 keeps this tube 25 in place.

The venturi with the abrupt shoulder 20 may beusedin either embodimentof the invention and the same is true of the annular recess 21, ring 22and coil spring 23. The plurality of' liquid fuel jets may also be usedin either embodiment of the invention and advantageous results areobtained with the movable venturi whether two or more liquid fuel jetsof different lengths are employed and Whether they are concentric witheach other or not.

Tests with the device indicate that with an abrupt shoulder as shown at20. in Fig. 2 a better mixture of gas and air is caused and the venturiappears to move to the different desired positions with greatercertainty than is the case with the shoulder omitted.

In the operation of the embodiment of the invention illustrated in Fig.1 when the venturi 8 is at its lowest or innermost position the smallestdiameter of it is approximately evenwith the tubes of the lowest rangejets 14 and 14'. This causes the exit ends ofthe low range jets 14 and14 toV be in a'high suction area and therefore when the motor is starteddischarge ofvr fuel takes place from these two jets. As the speed of themotor increases, due to control by the throttle 4, the suction.increases and when it reaches a point where it is sufficiently strongto move the venturi 8 outwardly and compress the spring 9, the venturimoves outwardly'. This causes the highl suction area or most restrictedportion of the venturi to be even with the tip of the next jet 13. Thestrong suction at this jet then causes fuel to'be drawn up the jet andout the discharge exit of it.

When this action takes place the low range jets 14 and 14 graduallycease to discharge fuel, as they are no longer in the highest suctionarea. As the throttle is opened farther and the suction becomes stillgreater, the venturi moves to its outermost position, thus causing thehigh suction area to be located near the exit end of the jet l2. Fuel isthen discharged from this jet While less fuel is discharged from the jet13 and very little, if any, from the jets 14 and 14'. Changes in theposition of the throttle 4 cause changes in the motor speed and suction.When the suction decreases the pressure springs 9 return the venturi8'.. By properly proportioning the parts and providing springs 9 of theright sort, a carburetor of this sort can be produced which is suitablefor any desired sort of service, thus causing feed of fuel from thedifferent jets in accordance with conditions of load and speed.

The operation of the embodiment of the device illustrated in Fig. 2 issomewhat similar to that already described. In this embodiment air isdrawn through the draft tube 33 at high velocity at the start, or at lowspeeds of the engine, thus causing fuel to be discharged from the jets30 and 30', the venturi 8' being aty its innermost position, thusleaving only a small annular space between the outer end of the drafttube 33 andthe opening through the venturi 8'. As the speed and suctionincrease and the venturi is moved outwardly, the discharge of fuelbegins to take place from the jet 28 and the discharge from the jets 30and 30' decreases as more air passes along the outside of the draft tube33. When the venturi 8 reaches its outermost or highest position thesmallest part of' the opening through it.v is some distance away fromthe upper end of the draft tube 33, thus causing fuel to discharge fromthe jet 25 and less from the other jets as more air then passes alongthe outside of the draft tube 33 instead of passingfthrough it.

What is claimed and desired to be secured by Letters Patent is z Acarburetorhaving a longitudinally movable venturi through whichvunobstructed fuel and' air pass, and fuel jets terminating at differentpositions within said venturi, the greatest difference between terminalsof said jets being substantially equal to the length of movement of saidventuri and a draft tube surrounding said jets and discharging into saidventuri.

FRED CJ. SCHRAMM.

